Further development of the Indium method, for detection antibodies to the various antigenic systems is described below. Tumor immunity. With a malignant sarcoma of Strain 13 animals, studies are under way to determine whether irradiated tumor cells will induce immunity. If not, we shall subject such cells to macrophage mash and to enzymes obtained from macrophage lysosomes for possible conversion of membrane antigens to fragments propitious for induction of cellular immunity, but inadequate for induction of (enhancing) antibodies. Histocompatibilty antigens. We will try to purify Strain 13 guinea pig H antigen by affinity columns using rabbit anti-H serum. With the purified antigen we hope to carry out a more effective complexing with a carrier molecule than has been possible. With carrier-H antigen we will try to induce preferentially an (enhancing) antibody response rather than cellular immunity. Sheep red blood cells as antigen. We shall subject these red cells to the action of macrophage lysosomal enzymes, to pronase and chymotrypsin, with attempted characterization of fragments of membrane antigens thus obtained, and will attempt induction of cellular immunity by permitting these fragments to adsorb to washed fresh macrophage membranes. Mechanism of action of adjuvant. We have extracted the water soluble adjuvant (WSA) from mycobacteria, and we shall test the effect of this on uptake of tritiated thymidine by T and B lymphocytes. We shall also measure the possible activating effect of this adjuvant upon macrophages, by studies of increase of lysosomal enzymes and of metabolic events. We shall extend our observations of the influence of cellular immunity upon the ability of macrophages to inhibit a bacterium (Listeria) by the use of an extraneous antigen (BGG) with mycobacteria (WSA).